GUT2, A GENE FOR MITOCHONDRIAL GLYCEROL 3-PHOSPHATE DEHYDROGENASE OF SACCHAROMYCES-CEREVISIAE

A gut2 mutant of Saccharomyces cerevisiae is deficient in the mitochon drial glycerol 3-phosphate dehydrogenase and hence cannot utilize glyc erol. Upon transformation of a gut2 mutant strain with a low-copy yeas t genomic library, hybrid plasmids were isolated which complemented th e gut2 mutation. The nucleotide sequence of a 3.2 kb PstI-XhoI fragmen t complementing a gut2 mutant strain is presented. The fragment reveal s an open reading frame (ORF) encoding a polypeptide with a predicted molecular weight of 68.8 kDa. Disruption of the ORF leads to a glycero l non-utilizing phenotype. A putative flavin-binding domain, located a t the amino terminus, was identified by comparison with the amino acid sequences of other flavoproteins. The cloned gene has been mapped bot h physically and genetically to the left arm of chromosome IX, where t he original gut2 mutation also maps. We conclude that the presented OR F is the GUT2 gene and propose that it is the structural gene for the mitochondrial glycerol 3-phosphate dehydrogenase.